Hi Luc nice setup you got there. Looks great! I'm also preparing to build a calcium reactor and was wondering how you connected the valves and the co2 hose connector at the bottom of the reactors in a watertight way since it is not a flat surface. Did you glue it or used some kind of rubber washer for sealing? Hope you can share some details.
I also live in Holland so maybe you willing to share the store you bought the parts?
Thanks and keep posting updates
I will try to make some pictures. But the process is relative straight forward because the buttom part of the tube (+cap) is thick and hence you have sufficient material to create a thread (1/4"). The thread is making sure the connection is water tight (and not the seal/area between the tube and connector. I used some thread seal tape (Teflon tape) to ensure it is and remains water tight.